Removable tamperproof fastening means

ABSTRACT

A head member is provided for a fastening means such as a screw, nut or bolt which can be turned in a direction to fasten the fastening means yet can be turned in a loosening direction only by a specially adapted tool. The head member has a transverse slot with two oppositely disposed shoulders which permit the turning of the head in a fastening direction. Two upwardly extending curved portions are provided which cause a slipping of a screwdriver when it is attempted to remove the fastening means. Removal is afforded by a notch extending into the head at the end of the slot which permits engagement by a projection on a specially adapted removing means.

United States Patent Herr [54] REMOVABLE TAMPERPROOF FASTENING MEANS[72] Inventor: George E. Herr, 2711 West Brown Street, Milwaukee, Wis.53205 22 Filed: Feb. 25, 1971 [21] Appl. No.: 118,888

[4 1 July4,1972

Primary Examiner-Marion Parsons, Jr. Attorney-Neil E. Hamilton andWilliam A. Denny [57] ABSTRACT A head member is provided for a fasteningmeans such as a screw, nut or bolt which can be turned in a direction tofasten the fastening means yet can be turned in a loosening directiononly by a specially adapted tool. The head member has a transverse slotwith two oppositely disposed shoulders which permit the turning of thehead in a fastening direction. Two upwardly extending curved portionsare provided which cause a slipping of a screwdriver when it isattempted to remove the fastening means. Removal is afforded by a notchextending into the head at the end of the slot which permits engagementby a projection on a specially adapted removing means.

8 Claims, 6 Drawing Figures PATENTEDJUL 4 m2 Inventor George EJ'ferrBACKGROUND OF THE INVENTION This invention relates to a tamperprooffastening means which can be removed by an especially adapted tool andmore particularly, to a tamperproof head for a screw, nut or bolt whichcan be fastened by a normal screwdriver head and is easily removed bythe provision of a small notch in the head of the screw at the end ofthe slot.

Screw type fastening means of the type concerned with in this inventionare described in US. Pat. Nos. 3,174,383; 1,956,963; 1,797,390 and1,300,275 and 610,423. US. Pat. No. 1,956,963 illustrates a one-wayscrew which is tamperproof and is fastened by an especially adaptedscrewdriver head. U.S. Pat. No. 3,174,383 describes a tamperproofsealing device for vending machines wherein a first screw head member isemployed to fasten a second screw. A double vei'tically slotted screw isdescribedin US. Pat. No. 610,423 and a screw threaded fastening meanswith a hole in the head is shown in US. Pat. No. 1,300,275. In U.S. Pat.No. 1,797,390 a screwdriver is described which is employed to be keyedon a screw with a hole in the center of a slot. There is availablecommercially a screw head having two oppositely disposed cammingsections with a slot in between for turning the screw in one directionfor fastening. The prior art nowhere teaches a removable tamperproofhead for a screw, bolt or nut which can be fastened by means of anordinary screwdriver yet can be removed by a simplified tool which canfit numerous sizes of such heads. Neither is there available atamperproof screw head which is readily fastened and also removedwherein the means of removal are not easily discemable.

It is an object of the present invention to provide a novel head for athreaded fastening means which can be fastened by an ordinaryscrewdriver yet can be removed only by a specially designed tool. It isanother object of this invention to provide a tamperproof threaded headmember wherein the means for removing or unfastening the head member isnot readily detected. It is still another object of the presentinvention to provide a threaded fastening means which is tamperproofwherein several sizes of such head members can be unfastened by a singletool. It is yet another object of this invention to provide a removabletamperproof fastening means which can be fabricated inexpensively andremoved easily, and without requiring expensively designed tools.

SUMMARY OF THE INVENTION The foregoing objects are accomplished and theshortcomings of the prior art are overcome by the present removabletamperproof fastening means which is comprised of a novel head portionand a threaded portion. Two oppositely disposed raised sections extendoutwardly from the head portion and each raised section is provided withopposing outwardly curved portions and shoulder abutment portions. Theshoulder abutment portions are spaced oppositely from each other andapart to form a slot across the surface of the head portion and there isat least one notch extending into the head portion from the periphery ofthe head at the end of the slot and adjacent to one of the shoulders. Atool having a projection and an elongated blade, such as at the end ofthe screwdriver, fits across the slot with the projections in the notchfor removing the fastening means. An ordinary screwdriver is employedfor fastening purposes.

BRIEF DESCRIPTION OF DRAWINGS A better understanding of the presentremovable tamperproof fastening means will be accomplished by referenceto the drawing wherein:

FIG. 1 is a perspective view of a screw with a head member having theunique tamperproof-removable feature and a screw portion engaging asection of wood with a strip of metal at the to FIG. 2 is a top view ofthe head member shown in FIG. 1 taken along line 2-2.

FIG. 3 is a perspective view of a nut and bolt arrangement with both thenut and bolt employing the removable tamperproof feature shown in FIG..1.

FIG. 4 is a top view taken along line 4-4 of FIG. 3.

FIG. 5 is a bottom end view taken along line 55 of FIG. 3.

FIG. 6 is a view in side elevation of a tool for removing the fasteningmeans shown in the previous figures and positioned over a head memberwith the removable tamperproof feature.

DESCRIPTION OF ONE EMBODIMENT Proceeding to a detailed description ofthe present invention, the removable tamperproof member generally 10 isillustrated for a screw and is comprised of a head portion 1 1 and athreaded stem portion 12 with the threaded stem portion being of thetypical tapering type. Extending upwardly and outwardly from the headportion 11 are two oppositely disposed and rounded and raised sections15 and 16 each having oppositely and outwardly curved portions 17 and18, respectively, which is best seen in FIG. 2. It will be noted thatthese two sections 15 and 16 each comprise approximately one-half of thesurface area of the head portion 11 and that two abutment, cotenninous,shoulder portions 20 and 21 are spaced oppositely from each other andapart to provide a slot 23 between the shoulder portions which taperfrom the center of the head to the periphery. A slightly raised shoulder24 is also disposed along upwardly and outwardly curved portion 17 toform a portion of slot 23. At the end of the slot 23 formed by the halfsections of the spaced apart shoulder abutment portions 20 and 21 is aU-shaped notch 25 which is formed entirely through the head member 11and at the end of the slot 23 and adjacent a shoulder 20. In FIG. 1, theremovable fastening means 10 is shown as engaged in a section of wood 28with the underside of the head 11 holding a thin layer of metal 29against the upper surface of the wood.

DESCRIPTION OF ANOTHER EMBODIMENT Referring to FIGS. 3, 4 and 5, tworemovable tamperproof fastening meansgenerally 110 and 210 areillustrated for a bolt and a nut, respectively. In FIGS. 3, 4 and 5common or similar parts as described in FIG. 1 are indicated by the samebasic numbers-except they are in the and 200 series for the nut and boltmembers, respectively. It will be recognized that the threaded shankportion 212 of the nut 210 is internally threaded and in effect is ofthe cap screw type. However, the head members 111 and 211 for bolt typefastening means and nut type fastening means 210 are exactly the same asfor screw type fastening means 10.

DESCRIPTION OF REMOVING TOOL Described in FIG. 6 is a tool generally 70for loosening or unthreading either the screw fastening means 10, thebolt fastening means 110 or the nut fastening means 210. It is similarto common screw driver with a gripping handle 71, a shank portion 72 anda flat blade section 73. One difference exists between the ordinaryscrewdriver and tool 70 in that a projection 75 extends outwardly on oneside of the tool 70 and in the same plane as the end engaging portion 76of the blade section 73.

OPERATION OF THE FIRST EMBODIMENT A better understanding of theadvantages of the removable tamperproof fastening type means 10 will behad by a description of its operation. Assuming it is desired to securea strip of metal 29 which could represent the flashing of a screen tothe underlying wood frame 28, a pilot hole would first be made throughmetal 29 into wood 28 and the threaded stem portion 12 inserted therein.A normal screwdriver (not shown) would then be employed with the end ofthe blade inserted in slot 23 between shoulder abutment portions 20 and21. As will best be seen in FIG. 1, when the screwdriver andconsequently the head member 11 is turned in a fastening clockwisemanner,

opposing portions of the blade section on the screwdriver will engagethe shoulder portions 20 and 21. Such turning will continue until thethreaded portion 12 is completely embedded in the wood 28 with theunderside of the head 11 firmly engaging the upper surface of the metalstrip 29. It will be noted that any attempt to turn the head member in acounter-clockwise manner with the normal bladed screwdriver having asingle planed end will result in the opposing end portions of the bladeriding up the oppositely disposed raised sections 17 and 18 which ineffect form cams. Thus, the removable tamperproof fastening means cannotbe removed with a normal screwdriver and if it is designed properly witha rather thin edge and the raised sections and 16 are properly rounded,they are not easily engaged with a pliers or gripping implement. When itis desired to remove fastening means 10, tool 70 will be employed withprojection 75 inserted into notch 25 and the end of 76 of blade 73aligned across slot 23. Fastening means 10 can now be turned in acounter-clockwise manner and unfastened as one side of projection 75will engage the counter-clockwise side 78 of notch 25 and the oppositeside of blade 73 will engage a portion of the shoulder section 20immediately adjacent to the notch as shown at 30. This is best shown inFIGS. 6 and 2. Of course, if desired, the tool 70 could be employed tosecure the removable tamperproof fastening means 10. However, forsecurity reasons it is best to limit the number of persons who know theoperation for removal and for ease of application it is more expeditiousto have the removable tamperproof fastening means 10 fastened by ascrewdriver.

OPERATION OF THE SECOND EMBODIMENT The manner of fastening either bolttype fastening means 110 or nut type fastening means 210 is exactly thesame as that described for screw type fastening means 10. The bolt andnut type fastening means 110 and 210 would be employed as would anyordinary nut and bolt with the items to be secured between the headmembers 111 and 211. The fastening and unfastening operation is aspreviously described for screw type fastening means 10 and all of theadvantages apply.

It should be noted in the foregoing description of the operation thatwhen a head member such as shown at 11, 111 or 21] is employed over asurface which has the same color as the head member that the notch 25,125 or 225 would be virtually indiscemable by the ordinary observer.This, of course, is a great advantage in that if the notch is not seenone would not pause to try to figure out how the head member might beengaged. Even if the notch is seen, it would take someone not having atool similar to that shown at 70 a goodly amount of eHort to make one orprocure one. It has definitely been proven that a large notch such as25, 125 or 225 is not necessary to turn a screw or bolt with a longthreaded stem portion. Thus, sufficient torque can be placed on the headand through the stem portions in order to turn the fastening member in aremovable manner.

As will be seen from the operation previously described, any of the headmembers are engaged by the ordinary single blade end of a screwdriver.This is an advantage in that one does not have to employ an especiallyadapted tool in order to fasten the screw, bolt or nut, employing thenovel tamperproof means. When it is desired to remove the members,authorized people can be supplied with the especially adapted tool 70which aids in additional security measures.

The removable tamperproof members can be provided on screws, nuts andbolts of varying sizes without limitation and the same is true of thethreaded stem portions. They can be composed of varying types ofmaterials such as hardened steel, aluminum, or rigid plastic materials.

It will thus be seen that through the present invention there is nowprovided a removable tamperproof fastening means which can be easilyfastened by the usual screwdriver yet can be removed only by means of anespecially adapted tool. The

tamperproof means is adaptable to varying sizes of normal screws, nutsor bolts and can be removed by slight adaptations to a normalscrewdriver. No expensive molding is required to design the screw, nutor bolt heads and readily available head members with tamperprooffeatures can be easily adapted for use with the novel notch feature.

The foregoing invention can now be practiced by those skilled in theart. Such skilled persons will know that the invention is notnecessarily restricted to the particular embodiments presented herein.The scope of the invention is to be defined by the terms of thefollowing claims as given meaning by the preceding description.

I claim:

1. A removable tamperproof fastening means comprising a head portion anda threaded stem portion, two oppositely disposed raised sectionsextending outwardly from said head portion, each said raised sectionprovided with opposing outwardly curved portions and shoulder abutmentportions, said shoulder abutment portions and said curved portionsspaced diametrically opposite from each other and apart to provide aslot across the surface of said head portions, said curved portionsextending outwardly from said slot and constructed and arranged to formcam surfaces to prevent engagement by a standard screwdriver whenturning in an unfastening direction and a single notch extending intosaid head portion from the periphery of said head portion at the end ofsaid slot and adjacent one said shoulder abutment portion whereby saidnotch and said adjacent shoulder abutment portion provide o posingengagement portions for turning said head in an unfastening direction.

2. The removable tamperproof fastening means as defined in claim 1wherein said threaded stern portion is of the pointed screw type.

3. The removable tamperproof fastening means as defined in claim 1wherein said threaded stem portion is of the bolt type.

4. The removable tamperproof fastening means as defined in claim 1wherein said threaded stem portion is of the extended, internallythreaded type.

5. The removable tamperproof fastening means as defined in claim 1wherein said notch extends completely through the head portion.

6. The removable tamperproof fastening means as defined in claim 1wherein each said raised portion comprises approximately quarter of theupper area of said head portion.

7. The removable tamperproof fastening means as defined in claim 7wherein said abutment portions are substantially cotemlinous.

8. The removable tamperproof fastening means as defined in claim 1wherein said head portions and said threaded stem portion is composed ofhardened steel.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORECTION Patent No.5,673,912 I Dated July 4, 1972 Inventor(s) George E. HBI'I It iscertified that error appears in the above-identified patent and. thatsaid Letters Patent are hereby corrected as shown below:

On the title page under "References Cited" "Foreign Patents orApplications" for the last-listed French patent delete "1,059,390" andsubstitute 1,059,399

In column 4, line 55, in :claim 6 before "quarter" insert one Signed andsealed this 2nd day of January 1973.

(SEAL) Attest:

- I ROBERT GOTTSCH EDWARD M.FLETCHER,JR. Commissioner 12L115 AttestingOfficer I 15 FORM PO'1050 (10-69) USCOMM-DC 60376-P69 U.5. GOVERNMENTPRINTlNG OFFICE I 1959 0*366'33

1. A removable tamperproof fastening means comprising a head portion anda threaded stem portion, two oppositely disposed raised sectionsextending outwardly from said head portion, each said raised sectionprovided with opposing outwardly curved portions and shoulder abutmentportions, said shoulder abutment portions and said curved portionsspaced diametrically opposite from each other and apart to provide aslot across the surface of said head portions, said curved portionsextending outwardly from said slot and constructed and arranged to formcam surfaces to prevent engagement by a standard screwdriver whenturning in an unfastening direction and a single notch extending intosaid head portion from the periphery of said head portion at the end ofsaid slot and adjacent one said shoulder abutment portion whereby saidnotch and said adjacent shoulder abutment portion provide opposingengagement portions for turning said head in an unfastening direction.2. The removable tamperproof fastening means as defined in claim 1wherein said threaded stem portion is of the pointed screw type.
 3. Theremovable tamperproof fastening means as defined in claim 1 wherein saidthreaded stem portion is of the bolt type.
 4. The removable tamperprooffastening means as defined in claim 1 wherein said threaded stem portionis of the extended, internally threaded type.
 5. The removabletamperproof fastening means as defined in claim 1 wherein said notchextends completely through the head portion.
 6. The removabletamperproof fastening means as defined in claim 1 wherein each saidraised portion comprises approximately quarter of the upper area of saidhead portion.
 7. The removable tamperproof fastening means as defined inclaim 7 wherein said abutment portions are substantially coterminous. 8.The removable tamperproof fastening means as defined in claim 1 whereinsaid head portions and said threaded stem portion is composed ofhardened steel.